硅基HgCdTe面阵焦平面器件结构热应力分析

红外焦平面器件是一个多层结构,包含外延衬底、HgCdTe芯片、Si读出电路、互连In柱、粘结胶以及引线基板等,由于各层材料之间的热膨胀系数不同导致焦平面器件在工作中承受很大的热应力,热应力是导致红外焦平面器件失效的重要因素之一。本文运用一维模型以及有限元分析方法对硅基HgCdTe320×240焦平面器件结构进行热应力分析,结果表明,改变Si衬底厚度、粘结胶的杨氏模量以及基板的热膨胀系数,都会不同程度地影响HgCdTe薄膜上的受力,其中基板的热膨胀系数对HgCdTe薄膜所受的应力影响最大。通过选用合适的基板可以有效降低HgCdTe薄膜所受的应力,从而降低器件失效率。

Thermal Stress Analysis of HgCdTe Focal Plane Arrays on Si Substrates

Infrared focal plane array(IRFPA) has a multilayer configuration which comprises of substrate,HgCdTe epilayer,Si readout IC,indium interconnects,epoxy and electrical lead board.The difference in thermal expansion between the layers has the potential to create large thermally induced stresses on the indium interconnects and the detector material.With repeated thermal cycling this can result in failure of the interconnects or lead to damage to the detector pixels.In the paper the thermal stress on HgCdTe FPA fabricated on Si substrate was analysed.The results showed that the thickness of Si substrate,the Young's modulus of epoxy and the coefficient of thermal expansion(CTE) of electrical lead board could influence the stress on HgCdTe layer,whereas the CTE of electrical lead board has the most important influence on the stress.